Generally speaking, modern automatic transmissions for motor vehicles offer the attractive capability of shifting the individual gears of the vehicle up or down manually as well. In other words, the driver can choose between two modes of operation, namely, automatic shifting operation and multi-step shifting operation. In order to select the modes of operation and the individual shifting stages (gears), in many cases, a selector lever is provided that can be pivoted into both shift lanes, namely, the automatic shift lane or the multi-step shift lane, in order to engage the selected shifting positions. Here, the two shift lanes, which are usually arranged in the lengthwise direction of the vehicle, are linked to each other in such a way that the selector lever can easily be pivoted from one shift lane into the other. When the selector lever is in the automatic shift lane, it can be pivoted into the familiar shifting positions D, N, R and P by actuating the gearshift and can be held in this position by locking means.
The desired shifting stage (gear) is selected by the specific position taken by the selector lever in the shift lane.
Here, in order to detect each of the positions of the selector lever, sensor elements are usually arranged as signal generators in a suitable place in the gear shifting gate. If a specific position of the selector lever is detected, then the signal generator located at that position sends a corresponding signal to the electronic control device of the automatic transmission. The evaluation of the switching signals in the automatic mode of operation or in the multi-step mode of operation as well as the actuation of the gears are carried out by the electronic control device.
When the selector lever is pivoted into the multi-step shift lane, the mode of operation “multi-step shifting mode” is activated by a signal or by a mechanical shifting procedure in the electronic control device of the automatic transmission.
The individual shifting stages (gears) can then be shifted up or down stepwise by means of the tip actuation of the selector lever. In this process, the tipping movement of the selector lever to shift up (+) or down (−) can likewise be detected by means of the signal generator and a corresponding switching signal is transmitted. Numerous proposals have been made for the technical configuration and improvement of a multi-step shifting control device used in automatic transmissions. Thus, DE 4217773 A1 describes a multi-step shifting control device of this generic type that can be operated by means of a selector lever in only one shift lane. The selector lever is divided in the middle so that the upper part can be moved under a slight deflection independently of the lower part. The switchover from automatic shifting operation to the multi-step shifting mode is effectuated here by actuating a manual switch that is arranged on the gear shifting gate and that engages with a locking pin that affixes the lower part of the selector lever. Now, as far as the pivoting range of the selector lever is concerned, the latter is locked in the lower pivoting point for automatic shifting, but in its spring-loaded middle position, it can be tipped at the middle pivot point within the range of spring defined by the contacts of the tip switch. The tip signals are transmitted to the electronic control device, which then triggers the manually initialized gear shifting procedures.
After the actuation of the tip switch, the selector lever is reset in the direction of the middle position of the gear shifting gate by a pressure spring mounted onto each tip switch.
A drawback of this arrangement has to do with the reliability of the mode of functioning of a divided selector lever that has to reliably assume a considerable number of shifting positions that are difficult to hold in place. The driver is also forced to operate an additional switch when changing into the multi-step shifting mode.
A number of recent developments disclose an arrangement that seems to be attractive to drivers, namely, two separate shift lanes in which contact-free semiconductor sensors are used to ascertain the position of the selector lever.
This is the case, for example, in DE 10022043 A1, where the position generators on the selector lever are configured as Hall generators and are mounted at the corresponding shifting positions. The multi-step shifting pulses to be transmitted to the gear control device are generated by the magnetic induction of a permanent magnet attached to the selector lever whose magnetic field reaches the detection area of the appertaining Hall sensor as a result of the shifting movements.
DE 19938528 A1 also discloses a control means for manually shifted automatic transmissions in which a selector lever can be moved in two shift lanes that are connected to each other. Hall sensors, in combination with a permanent magnet mounted on the selector lever, are once again proposed as position generators. The Hall sensors are arranged in the gear shifting gate and, like the selector lever gate, are always covered by shutters.
In this prior-art arrangements of multi-step shifting control devices, especially the sensor components, which are discrete and sensitive to external influences, are arranged relatively unprotected in the vicinity of the gear shifting gate. Moreover, the selective attachment, for example, of the position generators (sensors) or else of the permanent magnets on the frame components of the gear shifting gate and on the selector lever also require greater effort and more error-prone work during the assembly and adjustment of the automatic transmission selector.
Another state of the art is described in DE 4426207 C1. This invention likewise relates to a selector lever for an automatic transmission with two separate shift lanes, said selector lever having a projection in its lower section that, when pivoted into the multi-step shift lane, engages in a positive manner with the effective surfaces of the multi-step shifting means and transfers the mechanical shifting movement to the multi-step shifting means. In order to detect these selector lever movements, there is a sensor means (not described in greater depth there) which forwards the generated switching signals to a gear control device. In this case, the pivoting movements of the selector lever in the multi-step shift lane are made against the force of a spring (not shown there) that continuously returns the selector lever to the middle position after the tip shifting movement. The open construction likewise selected here probably entails drawbacks in terms of maintenance, reliability (fail-safe properties) and assembly work that are similar to the drawbacks of the other above-mentioned solutions.
EP 1036959 B1 describes a control means for electronic step-by-step shift control of an automatic transmission for motor vehicles in order to shift gears up and down by means of the tip actuation of a selector lever, said control involving optical sensors, an approach that requires a great deal of space. This system has the drawback that it cannot be diagnosed.
DE 102 27 633 A1 describes an encoded gear position switch that is suitable for an automatic transmission but not for automatic shifting with a tip function or a tip lane. This gear position switch does not have a mechanical resetting feature and is not configured with a modular design.
DE 697 06 449 T2 describes a gearshift means for a vehicle that is configured with a modular design and that has circuit boards. However, multi-track encoded magnets are not disclosed in this document.
DE 196 08 981 A2 describes a shifting device for the gears of motor vehicles whereby, during the shifting procedure, a selector lever is coupled to a control vane that reflects a signal that is detected by sensors and that is forwarded to a gear control device as a signal corresponding to the shifting position of the shifting lever. The shifting device is not configured with a modular design. A multi-track magnet is not disclosed in this document either.
DE 199 59 616 A1 describes a control device for a gearbox for automatic and manual shifting in a motor vehicle, in which there are two magnets, whereby one simple magnet serves for diagnostics in a normal shift lane and another magnet serves as the tip magnet. The control device has the drawback that two magnets are needed, which calls for a larger installation space and makes it more susceptible to malfunctions.